Mastodon is a free and open source microblogging platform similar to Twitter, but with user privacy and decentralization in mind. It’s one of many protocols that interacts with the Fediverse of protocols like Pleroma, GNU Social, and others. Unlike Twitter, Mastodon is not one social network.
You can use Mastodon with a web browser. Or you may prefer desktop software. Tootle is a GTK client for Mastodon. With the user experience in mind, it provides a clean, native interface that allows you to integrate Mastodon’s social experience seamlessly with your desktop environment.